[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2023-10-06 UTC."],[[["\u003cp\u003e\u003ccode\u003eFeatureCollection.merge()\u003c/code\u003e combines two FeatureCollections into a single FeatureCollection containing all elements from both.\u003c/p\u003e\n"],["\u003cp\u003eElements from the input collections retain their original properties but are given new IDs prefixed with "1*" and "2*" to distinguish their source.\u003c/p\u003e\n"],["\u003cp\u003eFor merging multiple collections, using \u003ccode\u003eFeatureCollection.flatten()\u003c/code\u003e on a collection containing all of them is recommended for better performance.\u003c/p\u003e\n"],["\u003cp\u003eRepeatedly using \u003ccode\u003eFeatureCollection.merge()\u003c/code\u003e can lead to decreased performance and excessively long element IDs.\u003c/p\u003e\n"]]],[],null,["# ee.FeatureCollection.merge\n\nMerges two collections into one. The result has all the elements that were in either collection.\n\n\u003cbr /\u003e\n\nElements from the first collection will have IDs prefixed with \"1*\" and elements from the second collection will have IDs prefixed with \"2*\".\n| **Note:** If many collections need to be merged, consider placing them all in a collection and using FeatureCollection.flatten() instead. Repeated use of FeatureCollection.merge() will result in increasingly long element IDs and reduced performance.\n\n| Usage | Returns |\n|----------------------------------------|-------------------|\n| FeatureCollection.merge`(collection2)` | FeatureCollection |\n\n| Argument | Type | Details |\n|---------------------|-------------------|---------------------------------|\n| this: `collection1` | FeatureCollection | The first collection to merge. |\n| `collection2` | FeatureCollection | The second collection to merge. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n// FeatureCollection of points representing forest cover.\nvar fcForest = ee.FeatureCollection([\n ee.Feature(ee.Geometry.Point([-122.248, 37.238]),\n {'id': 0, 'cover_class': 'forest'}),\n ee.Feature(ee.Geometry.Point([-122.204, 37.222]),\n {'id': 1, 'cover_class': 'forest'}),\n ee.Feature(ee.Geometry.Point([-122.110, 37.199]),\n {'id': 2, 'cover_class': 'forest'})\n]);\n\n// FeatureCollection of points representing urban cover.\nvar fcUrban = ee.FeatureCollection([\n ee.Feature(ee.Geometry.Point([-121.953, 37.372]),\n {'id': 0, 'cover_class': 'urban'}),\n ee.Feature(ee.Geometry.Point([-121.861, 37.308]),\n {'id': 1, 'cover_class': 'urban'}),\n ee.Feature(ee.Geometry.Point([-121.984, 37.372]),\n {'id': 2, 'cover_class': 'urban'})\n]);\n\n// Merge the two FeatureCollections into one.\nvar fcMerged = fcForest.merge(fcUrban);\n\n// Display FeatureCollections on the map.\nMap.setCenter(-122.034, 37.296, 11);\nMap.addLayer(fcForest, {color: 'green'}, 'Forest points');\nMap.addLayer(fcUrban, {color: 'grey'}, 'Urban points');\nMap.addLayer(fcMerged, {color: 'yellow'}, 'Protected areas merged');\n```\nPython setup\n\nSee the [Python Environment](/earth-engine/guides/python_install) page for information on the Python API and using\n`geemap` for interactive development. \n\n```python\nimport ee\nimport geemap.core as geemap\n```\n\n### Colab (Python)\n\n```python\n# FeatureCollection of points representing forest cover.\nfc_forest = ee.FeatureCollection([\n ee.Feature(\n ee.Geometry.Point([-122.248, 37.238]),\n {\n 'id': 0,\n 'cover_class': 'forest',\n 'id': 0,\n 'cover_class': 'forest',\n },\n ),\n ee.Feature(\n ee.Geometry.Point([-122.204, 37.222]),\n {\n 'id': 1,\n 'cover_class': 'forest',\n 'id': 1,\n 'cover_class': 'forest',\n },\n ),\n ee.Feature(\n ee.Geometry.Point([-122.110, 37.199]),\n {\n 'id': 2,\n 'cover_class': 'forest',\n 'id': 2,\n 'cover_class': 'forest',\n },\n ),\n])\n\n# FeatureCollection of points representing urban cover.\nfc_urban = ee.FeatureCollection([\n ee.Feature(\n ee.Geometry.Point([-121.953, 37.372]),\n {'id': 0, 'cover_class': 'urban', 'id': 0, 'cover_class': 'urban'},\n ),\n ee.Feature(\n ee.Geometry.Point([-121.861, 37.308]),\n {'id': 1, 'cover_class': 'urban', 'id': 1, 'cover_class': 'urban'},\n ),\n ee.Feature(\n ee.Geometry.Point([-121.984, 37.372]),\n {'id': 2, 'cover_class': 'urban', 'id': 2, 'cover_class': 'urban'},\n ),\n])\n\n# Merge the two FeatureCollections into one.\nfc_merged = fc_forest.merge(fc_urban)\n\n# Display FeatureCollections on the map.\nm = geemap.Map()\nm.set_center(-122.034, 37.296, 11)\nm.add_layer(fc_forest, {'color': 'green'}, 'Forest points')\nm.add_layer(fc_urban, {'color': 'grey'}, 'Urban points')\nm.add_layer(fc_merged, {'color': 'yellow'}, 'Protected areas merged')\nm\n```"]]
